Optimized synthesis of banana peel derived porous carbon and its application in lithium sulfur batteries

KOH activation was applied to obtain hierarchical porous carbons from banana peels. The influence of alkali/carbon ratio and activation temperature on pore feature and electrochemical performance of C/S composites was investigated. Pore volume was found to have a positive correlation with discharge capacity and cycle stability and an inverse correlation to overall impedance. Porous carbon with largest pore volume of 2.04 cm³ g⁻¹ obtained at alkali/carbon ratio of 3.5 and 800 °C was able to accommodate 65 wt.% sulfur. Highest discharge capacity of 796 mA h g⁻¹ was delivered at 0.5 C and 80.5% of it was kept after 100 cycles. After 500 cycles, the composite still delivered a high discharge capacity of 615 mA h g⁻¹, indicating superior cyclestability. Optimization on sulfur content in C/S composite was explored and 65 wt.% was found to be the best proportion. Both too low and too high sulfur content resulted in inferior electrochemical performance.